Invisible multifocal lens

ABSTRACT

Invisible bifocal sunglasses. The sunglasses include a hard mirror coating to disguise the different focal powers of the sunglasses. The bifocal sunglasses also include a bifocal region that is molded within the main lens blank of the sunglasses.

RELATED APPLICATIONS

This application is a divisional of pending application Ser. No.10/711,756, filed on Oct. 1, 2004.

FIELD OF THE INVENTION

This invention relates to the field of multifocal sunglasses andparticularly to bifocal sunglasses having a non-magnified portion and anon-prescription magnified portion.

BACKGROUND OF THE INVENTION

Sunglasses are widely recommended and used when individuals are indirect or indirect sunlight. The protective effect provided bysunglasses is important to mitigate the health risks associated withoverexposure of the eyes to sunlight, particularly the ultraviolet (UV)component thereof. It is well known that overexposure to ultravioletradiation from the sun can cause or exacerbate cataracts, for example.

Another problem arises due to the glare from direct or reflectedsunshine with most outdoor activities. Sunglasses are critical inminimizing glare from sunlight or reflected surfaces. Driving, boating,flying or just general activities in bright sunlight often cannot besafely performed without sunglasses.

Another feature that is typical of many wearers of sunglasses is thestylistic or aesthetic look of the sunglasses. Sunglasses are oftenconsidered a fashion accessory as well as utilitarian item. Thus, thestyle of the sunglasses may be as important as the relevant healthmitigation that the sunglasses may provide.

Prescription sunglasses are often worn by people who have deficienciesin their vision. Many people suffer from eye problems, such as myopia,presbyopia or astigmatism that require corrective eyewear. Often, thecorrective eyewear is incorporated into sunglasses. Such prescriptionsunglasses provide not only the health benefits from overexposure tosunlight, but also correct the eyesight of the wearer.

However, a problem often arises with people who may want to read orperform activities that require a change in their prescriptive eyewear.Many people have differing corrective vision requirements for fardistance and near distance viewing. Often, multifocal eyewear lenses areprovided for this need. Multifocal eyewear lenses are defined as lensesthat include two or more regions or lens portions and where at least oneof those regions has a magnified focal power. Multifocal lenses includebifocal lenses where at least one portion is magnified and the otherportion has a differing focal power such as piano (non-magnified) orelse magnified or otherwise adjusted to corrective the wearer's vision.Multifocal lenses may also include trifocal, progressive addition or anyother type of eyewear lenses that has at least one portion that isintended for corrective vision purposes.

Bifocal eyewear provides a region in the upper and/or central region ofthe eyeglasses that is either piano or has a corrective focal power forfar distance viewing and a lower region having a magnified focal powerfor near viewing needs. Other types of multifocal lenses may be used forother vision requirements, such as trifocal lenses. Another lens type isfor people that suffer only from presbyopia. Presbyopia is the inabilityof the eye to focus at objects up close, generally within 36 inches.This individual has a choice of using a single magnification throughoutthe entire lens that allows them to read close up or have a bifocal atthe bottom of the lens coupled with a non magnified upper area (calledpiano) of the lens. These glasses are called reading glasses and do notrequire prescriptions.

While this is more than adequate for indoor and night use, there isoften a need for multifocal eyewear in direct sunlight. For example,many people enjoy reading or other activities that require near visionwhile on the beach or otherwise outdoors. Another example for such needsincludes outdoor equipment operators, such as boating, that requiresviewing of displays, maps and other near vision requirements whilerequiring non magnified (piano) far vision viewing for the fulloperation of the equipment.

One solution in satisfying this need is people may use a clip-onsunglass over the top of their existing bifocals or full lens readingglasses. Problems arise with the use of clip-on sunglasses however. Itrequires a separate purchase and clip-on's are not readily available inthe style of the glasses they need to work with. Another problem is theattachment mechanism of the clip-on sunglasses to the bifocal eyewear.These attachment mechanisms tend to easily become disengaged atinopportune times. Another problem is that the eyewear becomes topheavy, unbalanced and cumbersome. Yet another problem is that theclip-on sunglasses destroy the aesthetic appeal of the eyewear.

There have been some attempts in the past to provide bifocal sunglasses.These attempts have created a relatively unattractive design. Thebifocal sunglasses are readily evident by casual observation by the lineof demarcation between the differing focal regions. Since sunglassestend to be selected for stylistic reasons first and then health reasons,sunglasses with bifocals have not been popular in the past. Also, manypeople prefer that their vision deficiencies not be readily noticeable.

Previous bifocal sunglasses have a three-dimensional appearance. Thislook is due to the addition of a bifocal lens adhered either onto theinner surface or the outer surface of the sunglasses. These bifocalsunglasses are easily noticeable to the casual observer. As such, thesesunglasses are undesirable to most individuals.

Thus the need exists for multifocal sunglasses that are notdistinguishable from other sunglasses and particularly for bifocalsunglass lenses which have a magnified portion on the bottom with anon-magnified lens on top.

SUMMARY OF THE INVENTION

The present invention provides a solution for these and other problemsby providing sunglasses that substantially disguise the focal power ofnon-prescriptive bifocal sunglasses. In the preferred embodiment, evenmultifocal sunglasses are essentially indistinguishable to a casualobserver.

A preferred embodiment of the present invention provides a pair ofsunglasses that have non-prescriptive lenses with a magnified lensportion to correct deficient presbyopic eyesight. The sunglasses includea light transmittance blocking mechanism, such as dye pigmentation or anultraviolet coating. The sunglasses also include a flash mirror coatingto disguise the non-prescriptive bifocal nature of the lenses.

Another preferred embodiment of the present invention provides a uniquemultifocal lens that incorporates lens of differing focal powers withinan outer lens. This minimizes the appearance of the differing focalpowers in the eyewear, particularly in sunglasses.

The present invention, in another preferred embodiment, uses thecombination of the lens within a lens multifocal lens with the flashmirror coating to disguise the appearance of multifocal sunglasses.

The present invention also provides in a preferred embodiment arelatively thin, high strength acrylic or polycarbonate lens for use asnon-prescriptive bifocal sunglasses. The thin plastic acrylic orpolycarbonate lenses are coated with a hard metallic coating to provideadditional strength to the lens.

The multifocal sunglasses are, in a preferred embodiment, manufacturedby a unique manufacturing process that simultaneously injection molds inan inner focal power lens blank and an outer piano lens blank. Eachdifferent focal power of lens uses a unique mold. These lens blanks arethen dyed with light transmittance blocking pigmentation. The dyedlenses are then coated with a light flash mirror coating in a vacuumcoating machine. This metallic coating provides not only additionalstrength to the lens but also disguises the inner focal power of thelenses.

The multifocal sunglasses are then essentially indistinguishable fromall other sunglasses by casual observance. The metallic coating may beused with single focal as well as multifocal lenses manufactured byother processes as well. These non-prescriptive bifocal sunglasses withthis coating process may be manufactured as thinner lenses as thecoating provides additional strength to the lenses as well as providinga durable coating.

These and other features of the present invention will be evident fromthe ensuing description of preferred embodiments and from the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an example of the multifocal sunglassesof a preferred embodiment of the present invention.

FIG. 2 is a front view of the multifocal sunglasses of a preferredembodiment of the present invention.

FIG. 3 is a top view showing the inner surface of the lenses of themultifocal sunglasses of the embodiment of FIG. 2.

FIG. 4 is front view of a lens blank manufactured under a preferredembodiment of the present invention.

FIG. 5 is a rear view of the lens blank of FIG. 4.

FIG. 6 is a chart of the light transmittance of the preferred embodimentof the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

The present invention, in a preferred embodiment, provides improvedaesthetics of nonprescription bifocal sunglasses. A preferred embodimentof the present invention is described below. It is to be expresslyunderstood that this descriptive embodiment is provided for explanatorypurposes only, and is not meant to unduly limit the scope of the presentinvention as set forth in the claims. Other embodiments of the presentinvention are considered to be within the scope of the claimedinventions, including not only those embodiments that would be withinthe scope of one skilled in the art, but also as encompassed intechnology developed in the future.

The present invention is described herein as bifocal eyewear. It is tobe expressly understood that other types of eyewear may be used as well,including single focal eyewear, trifocal eyewear, progressive additionlenses, other multifocal lenses, and any other types of eyewear,prescriptive and non-prescriptive. Multifocal eyewear lenses are definedfor purposes of this application as lenses that include two or moreregions or lens portions and where at least one of those regions has amagnified focal power. Multifocal lenses include bifocal lenses where atleast one portion is magnified and the other portion has a differingfocal power such as piano (non-magnified) or else magnified or otherwiseadjusted to correct the wearer's vision. The magnified portion may beprescription or non-prescription. Multifocal lenses may also includetrifocal, progressive addition or any other type of eyewear lenses thathas at least one portion that is intended for corrective visionpurposes.

A preferred embodiment of the present invention is illustrated in FIGS.1-3. Prescription bifocal sunglasses 10 include frame 12 and lenses 20,22. For purposes of this invention, the frames 12 are not a criticalcomponent of the invention. Any frame that is compatible for use witheyewear is considered to be within the scope of the claimed invention.

This preferred embodiment includes bifocal lenses 24, 26 incorporatedinto the lenses 20, 22, respectively. The lenses 20, 22 in thispreferred embodiment are piano lenses, that is non-magnified. Thebifocal lenses 24, 26 in this preferred embodiment are non-prescriptionmagnified lenses. It is to be expressly understood that other types oflenses may be included in the present invention as well, includinglenses have two or more regions of differing focal powers, includingprescription lenses.

The above described bifocal lenses 24, 26 are incorporated directly intothe lenses 20, 22 through a process described in greater detail below.The lenses are treated with a dye coating to limit the lighttransmittance as described in greater detail below. Preferably, thelight transmittance is between the range of about ten to forty percent,although the specific range of between twelve to fifteen percent ispreferable. The range may also be expanded as necessary to accommodatespecialty uses.

This preferred embodiment also includes a flash mirror coating 30 on theexterior of the lenses. The flash mirror coating provides a durablefinish over the lenses that also minimizes the appearance of the bifocallenses 24, 26 relative to the lenses 20, 22.

The combination of the flash mirror coating 30 over the lenses 20, 22,24, 26 and the incorporation of the bifocal lenses 24, 26 into thelenses 20, 22 render the appearance of the differing focal lenses nearlyinvisible. The sunglass lenses will appear to be simply non-prescriptivenon-magnified sunglasses to the casual observer. It is nearly impossibleto discern that the eyewear is multifocal or even bifocal eyewearwithout careful inspection.

Preferred Embodiment of the Multifocal Lens Manufacturing Process

In this preferred embodiment, the lenses 20, 22 are precision moldedfrom plastic resins. These plastic resins may include CR-39, a wellknown plastic eyeglass lens material, polycarbonate, Zyl resin, or anyother suitable material. In this preferred embodiment, the preferredmaterial is acrylic. These plastic resins are heated and injected intomolds. The lens blanks that are formed from the molding process are atthis point clear lenses. The lens blanks are then cooled, and inspectedfor scratches, dents and other molding impurities.

The multifocal lenses 20, 22, 24, 26 are formed in a unique moldingprocess in a preferred embodiment of the present invention. The moldingprocess utilizes an inner mold within the outer lens blank mold. Theinner mold creates the bifocal powered focal lens 24, 26 within the lensblanks 20, 22. Different focal powers for the bifocal lens 24, 26 arecreated by different inner molds. In operation, the outer mold createsthe lens 20, 22 in an injection molding operation. Simultaneously withthe molding of the outer lenses 20, 22, an inner mold contained withinthe outer mold also is injected with the plastic resins. A differentmold is used for each different focal power of lens that ismanufactured, both for the outer lens and for the inner lens.

The bifocal or multifocal lenses are contained largely within the lenses20, 22 as shown in FIG. 4 and 5. This minimizes the appearance of thediffering focal regions of the multifocal lenses. The difference in thefocal powers to the extent that it is noticeable is primarily noticeableon the inner surface of the lenses. Previous multifocal lenses typicallyincluded a line of demarcation between the lenses that clearly indicatedthat these were multifocal eyewear. Even progressive multifocal lensesthat blend the regions of differing focal power to eliminate this linestill are clearly noticeable as multifocal eyewear. Adding lighttransmittance blocking pigmentation or coatings fail to minimize thisappearance of the previous multifocal eyewear.

It is to be expressly understood that other types of manufacturingmultifocal lenses are considered to be within the scope of the presentlyclaimed invention. For example, the multifocal lenses may be created bygrinding different regions of the lens to different powers, by adheringdifferent layers of optic glass or plastic to one another, by thermalvacuum forming where a glass or plastic blank is positioned onto aplatform within a furnace to form the lens and bifocal region either byvacuum or by gravity or by any other type of manufacturing processcurrently utilized or later developed.

Once the lens blanks have been manufactured, they are inspected forscratches, dents and for other impurities or defects that may haveoccurred during the molding process.

The accepted lens blanks are then dyed with pigments to block lighttransmittance within acceptable limits. The overall light transmittancein the preferred embodiment ranges within about ten percent to aboutforty percent as shown in FIG. 4. In the preferred embodiment, thepreferred transmittance is about twelve to fifteen percent for outdooruse and to block UV400 rays including UVA and UVB light. Other rangescan be specified for other uses if necessary. Also, other dyepigmentation may be used to provide uses for different environments. Forexample, it may be useful to provide light transmittance of certainwavelengths while blocking other wavelengths for low light use,reflected light, polarization or any other desired uses.

The dyed lens blanks are then treated with a hard metallic coating. Anumber of different metallic coatings may be used. In the preferredembodiment, the lens blanks are coated with chromium. In this preferredembodiment, the lens blanks are coated in a vacuum coating machine witha light flash mirror coating.

The coating provides a number of benefits. Among these benefits is theadded strengthening of the lens blank. This allows a thinner lens blankto be manufactured which improves the aesthetic styling of thesunglasses. The preferred acrylic material of the lens blank isrelatively thin when used in eyewear. The metallic coating providesadditional strength to allow a thin lens to be manufactured even forrelatively strong focal powers.

The metallic coating of the preferred embodiment also provides a flashmirror coating to the external surface of the lenses. This flash mirrorcoating disguises the different focal regions of the lenses as well asthe look of prescriptive eyewear. The preferred embodiment of thepresent invention utilizes this flash mirror coating with the bifocallens molded within the outer lens to provide essentially invisiblemultifocal sunglasses. In this embodiment, the bifocal lens 24 is onlynoticeable from the inner surface of the eyewear, and then only uponclose inspection.

It is to be expressly understood that this flash mirror coating processmay be used with multifocal lenses manufactured by other techniques aswell.

Once the lens blanks have been coated with the light flash mirrorcoating, the lens blanks are tested for ultraviolet transmission. Theacceptable lens blanks can then be edged and cut to an appropriate sizeto fit into specified frames. The lenses can then be inserted intoframes with the specified pupillary distance for a wearer.

It is to be expressly understood that the above described embodimentsare provided for explanatory purposes only. Other embodiments areconsidered to be within the scope of the present invention as claimed.

1. A lens assembly for sunglasses, said lens assembly comprising: anouter lens having a first focal power; an inner lens affixed within saidout lens and having a second focal power; a dye pigmentation forblocking light transmission through said lens assembly; and a mirrorcoating on said outer lens to disguise said the differences in saidfirst focal power of said outer lens and said second focal power of saidinner lens.
 2. The lens assembly of claim 1 wherein said mirror coatingfurther includes: a hard coating for abrasion resistance; and providingadditional strength to said outer lens.
 3. The lens assembly of claim 1wherein said coating includes: providing the appearance of a light flashmirror.
 4. The lens assembly of claim 1 wherein said coating includes:chemicals having chromium as one ingredient.
 5. The lens assembly ofclaim 1 wherein said outer lens including: focal power objects toimprove visual acuity; and said mirror coating disguises said focalpower objects on said outer lens to an observer.
 6. The lens assembly ofclaim 1 wherein said lens assembly includes: said outer lens having anon-magnified focal power; said inner lens having a differing focalpower than said outer lens; said inner lens is molded into said outerlens; and said hard coating disguises the differing focal powers of saidouter lens and said inner lens to an observer.
 7. The lens assembly ofclaim 1 wherein said dye pigmentation for said lens assembly limits thelight transmittance through said lens assembly approximately between tento forty percent.
 8. The lens assembly of claim 1 wherein said dyepigmentation for said lens assembly limits the light transmittancethrough said lens assembly to about approximately twelve to fifteenpercent.